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Indicator Assessment
Fragmentation pressure of urban and transport infrastructure expansion
Note:
Classes represent the number of meshes per 1 000 square kilometres. Light colours mean less fragmentation pressure and dark colours mean more fragmentation pressure exerted by urban and transport infrastructure expansion.
Large parts of Europe have become highly fragmented as a result of the expansion of urban and transport infrastructure. Areas under great pressure of fragmentation are often found around large urban centres and along major transport corridors (Figure 1). The highest levels of fragmentation are found in the Benelux countries, followed by Malta, Germany and France (Figure 2). In these countries, the strong and very strong fragmentation classes account for over 60 % of their area (Luxembourg 93 %, Belgium 80 %, Netherlands 67 %, Malta 62 %, Germany 60 %, France 60 %). These countries indicate fragmentation hotspots at the European scale.
The United Kingdom has a heterogeneous fragmentation pattern and provides a good example of landscape fragmentation dominated by urban centres (EEA / FOEN, 2011). The areas around London show higher levels of fragmentation, similar to Benelux countries, whereas the Scottish Highlands are among the least fragmented areas in Europe (Figure 1 and the map showing the "Percentage of NUTS3 regions covered by high and very high fragmentation pressure classes").
On the outer boundaries of Europe, fragmentation levels are lower than in the centre of the continent. South-eastern Europe and Scandinavia show the lowest degree of fragmentation, with around 40 % of the countries’ territories in the low fragmentation class (e.g. the former Yugoslav Republic of Macedonia, Iceland, Montenegro, Norway and Sweden). This pattern could change drastically in the future because of ambitious road building plans in eastern and central Europe. Poland, for instance, has an unprecedented motorway building programme, which represents 40 % of the road building market in the region for the coming years (EEA, 2011). This may further fragment habitats unless measures are taken to preserve connectivity and compensate habitat loss
Over time the Mediterranean region has developed a unique blend of tourism activities related to the sea and coastal areas, health, sports, nature, business and culture, which offers consistent employment opportunities (11.5 % of total employment) and wealth (11.3 % of regional GDP) (WTTC, 2015). Nevertheless, Mediterranean countries are less fragmented than countries in central and western Europe, although there are differences between the western and the eastern Mediterranean regions. A higher degree of fragmentation is seen in Italy, the Mediterranean part of France and along the coasts of Spain, where the development of tourism is already mature. Eastern Mediterranean countries on the other hand are under less pressure from fragmentation. However, they are also affected by coastal fragmentation due to blooming tourism industry, as seen in Albania, Bosnia and Herzegovina, Croatia, Montenegro, Slovenia and Greece (Plan Blue, 2016).
The spatial pattern of fragmentation as a result of urban and transport infrastructure in Europe corresponds with the degree of urbanisation: cities are more fragmented than towns, which in turn are more fragmented than rural areas (Figure 3). The difference between cities and other areas in Europe in terms of very strong fragmentation pressure is greater than the difference between towns and rural areas.
As the pressure of fragmentation from urban and transport expansion in cities and towns is expected to be high, rural areas are more informative in terms of assessing fragmentation pressures. The Spatial pattern of fragmentation pressures in rural areas map shows the heterogeneous nature of rural areas in European countries. Central and western European countries have a high percentage of highly or very highly fragmented rural areas, whereas the lower fragmentation class is practically non-existent in Belgium, Denmark, the Netherlands, Germany, Luxembourg, the Czech Republic and Poland. In the Scandinavian countries on the other hand, fragmentation is very low in at least 25 % of rural areas.
As expected, regions with a higher population density (i.e. more than 100 inhabitants per square km) are generally more fragmented (see Figure 4 and the Fragmentation pressure and population density in EEA member countries map). However, the assessment also shows that many sparsely populated regions in Europe are also under high landscape fragmentation pressure. For example, 50 % of sparsely populated areas (< 100 resident population per square km) in France are under high fragmentation pressure, while this value is almost 70 % in Luxembourg. In the Nordic countries, densely populated areas under high fragmentation pressure only account for 10 % of the countries' areas. In fact, even the most fragmented regions in Finland and Norway have a relatively low level of fragmentation when compared with most European regions.
References:
Eurostat, 2014. Degree of urbanisation, 2014
EC, 2014, A harmonised definition of cities and rural areas: the new degree of urbanisation
The proportion of the Atlantic and Continental regions under high and very high fragmentation pressure from urban and transport expansion is the highest in Europe, i.e. 50 % and 40 % respectively of their area is fragmented (Figure 5).
The Alpine, Arctic and Macaronesian regions are the least fragmented. In around 80 % of these regions, fragmentation is very low with only 3 % or less of their area highly or very highly fragmented.
Croplands (i.e. regularly or recently cultivated areas [1]) and grasslands are the most fragmented ecosystems in Europe (Figure 6). More than 30 % of croplands and around 25 % of grasslands are highly or very highly fragmented by urban and transport expansion. Most of these ecosystems are used for agriculture, so they are subjected to high levels of management, hence, this high degree of fragmentation can be expected. Both ecosystems are under the highest fragmentation pressure in the Atlantic and Continental regions. Grasslands located in these two regions represent 50 % of European grasslands, with around 40 % of their area under high or very high fragmentation pressure. The lowest fragmentation pressure on both ecosystem types can be found in the Anatolian and Black See regions.
Forested ecosystems cover more than 40 % of the European land surface and hence are one of the largest terrestrial ecosystems in Europe. The increase in forest cover over the last 20 years has occurred at an annual rate of 0.8 %, although this does not necessarily enhance forest connectivity (Forest Europe, 2011; EEA, 2015; EEA 2016). The current assessment shows that 12 % of forests in the 39 EEA member countries are highly fragmented as a result of urban and transport expansion. Forest ecosystems within the Atlantic and Continental regions are under the greatest fragmentation pressure: around 30 % of their area is highly or very highly fragmented in these regions. If the Arctic and Macaronesian regions are ignored because they are so small, forests in the Alpine region are under the lowest pressure of fragmentation, by far. In 70 % of forests in the Alpine region, fragmentation is very low.
In contrast, around 50 % of heathlands, scrub and tundra ecosystems and of mires, bogs and fens are under low fragmentation pressure and hence are the least fragmented ecosystems in Europe.
[1] Following the MAES ecosystem types classification
References:
EEA, 2015. Fragmentation of natural and semi-natural areas. SEBI 013. European Environment Agency.
EEA, 2016: European forest ecosystems - State and trends. EEA Report No 5/2016
Estreguil, C., Caudullo, G., de Rigo, D. & San-Miguel-Ayanz, J., 2012. Forest landscape in Europe: Pattern, Fragmentation and Connectivity. JRC scientific and policy report EUR 25717EN. Luxembourg: Publications Office of the European Union. doi: 10.2788/77842.
Forest Europe, 2011. Status and Trends in Sustainable Forest Management in Europe. Ministerial Conference on the Protection of Forests in Europe. FOREST EUROPE, UNECE and FAO. Joint report. ISBN 978-82-92980-05-7.
Maes, J. et al., 2016. An indicator framework for assessing ecosystem services in support of the EU Biodiversity Strategy to 2020. Ecosystem Services, Volume 17, pp. 14-23.
The Nature Directives (Birds and Habitats) are the centerpiece of the EU’s nature legislation and biodiversity policy. The Natura 2000 sites are one of the Nature Directive's main tools that contribute to ensuring the conservation of many species and habitats of EU interest.
Fragmentation pressures within Natura 2000 areas were compared with fragmentation pressures in buffers surrounding the Natura 2000 sites.
In the EU as a whole, the pressures of urban and transport expansion that lead to fragmentation are lower in Natura 2000 sites than in their surroundings (Figure 7). The area in which the fragmentation pressure class is high or very high accounts for less than 10 % of all Natura 2000 sites; very high fragmentation pressure represents just a few percent of all Natura 2000 sites. In contrast, around 20 % of the immediate surroundings of Natura 2000 sites are exposed to high and very high fragmentation pressures.
All EU countries have a lower level of fragmentation inside their Natura 2000 sites than in their buffering areas (see Figure showing Fragmentation pressure within and outside of Natura 2000 areas per country). The largest difference between high fragmentation pressure in Natura 2000 sites and in their buffers can be seen in Germany, France and Italy. In Bulgaria, Finland, the Netherlands and Spain, much larger areas show very low fragmentation values within the Natura 2000 sites compared with their buffers.
The observations made above may reflect the following evidence (EEA 2012):
Therefore, comparison between countries is complex and differences in fragmentation of Natura 2000 sites cannot be fully explained by the protection regime of the network. More interesting and useful from a policy point of view will be to analyse the evolution of fragmentation over time rather than compare countries, regions or protection regimes at a given point in time.
This indicator is based on the Effective Mesh Size (Jaeger 2000) method. For some species, the effective mesh size (meff) can be interpreted as the area that is accessible when beginning to move from a randomly chosen point inside a landscape without encountering man-made barriers such as transport routes or built-up areas. However, it should be stressed that for many species that can fly, or are effective dispersers in others ways, man-made structures may not act as barriers.The combination of all barriers in a landscape is called Fragmentation Geometry (FG) hereafter.
The meff value expresses the probability that any two points chosen randomly in an area are connected. Hence, meff is a measure of landscape connectivity, i.e. the degree to which movements between different parts of the landscape are possible. The larger the meff, the more connected the landscape. The indicator addresses structural connectivity of the landscape and does not tackle functional, species specific connectivity.
The Effective Mesh Density (seff) is a measure of landscape fragmentation, i.e. the degree to which movement between different parts of the landscape is interrupted by Fragmentation Geometry. It gives the effective number of meshes (or landscape patches) per 1 000 km2, in other words, the density of the meshes. The seff value is calculated as 1 000 km2/meff, hence, the number of meshes per 1 000 km2. The more barriers fragmenting the landscape, the higher the effective mesh density.
meff and seff are reported within the cells of a 1 km2 regular grid.
meff is area-proportionally additive, hence it characterises the fragmentation of any region considered, independently of its size, and thus can be calculated for a combination of two or more regions. The meff has several advantages over other metrics:
meff values are positive real numbers including 0 for grid cells completely covered by urban areas and infrastructure (i.e. the landscape is covered by impermeable surfaces). The lower threshold for meff is 0.000001 km2 (= 1 m2), and smaller values are rounded to this latter value. The highest possible value of meff is limited by the area of the landscape patches as well as by the area of the Fragmentation Geometry affecting the landscape patches. A landscape patch is defined as a continuous area with the barriers of the Fragmentation Geometry as boundaries. Hence, the largest meff value will be assigned to the largest continuous landscape patch with the smallest area taken up by the Fragmentation Geometry (see illustration of meff calculation).
The seff values are positive real numbers. If meff = 0.000001 km2, then seff = 1 000 000 000 meshes per 1 000 km2. For grid cells completely covered by built-up areas and infrastructure (i.e. where meff = 0 km2), the seff value is set to -2, i.e. -2 represents positive infinity.
For convenience and practical considerations, meff values < 0.01 km2 = 10 000 m2 are rounded to 0 as these values are too small to be measurable without noise on a European scale. As a consequence, the largest reported seff values are 100 000 (= 1 000 km2/0.01 km2) meshes per 1 000 km2.
The indicator presents the effective mesh density (seff) values because these are more intuitive to understand as fragmentation. For the assessment, the continuous seff values were grouped into 5 fragmentation classes (very low, low, medium, high, and very high) according to the following steps:
(1) Selecting 95 % of the seff value range (ignoring the upper and lower 5th percentiles)
(2) Running the geometric interval classification.
(3) Rounding threshold values for straightforward comparison and change detection.
The thresholds for the fragmentation classes are:
|
seff values [number of meshes per 1000 km2] |
Fragmentation class |
|
(0 – 1.5] |
Very low |
|
(1.5 – 10] |
Low |
|
(10 – 50] |
Medium |
|
(50 – 250] |
High |
|
> 250 seffs |
Very high |
Priority objective 1, paragraph 23, of the Seventh Environment Action Programme (7th EAP) explicitly lists fragmentation as one of the key elements to protect, conserve and enhance the Union’s natural capital: 'The degradation, fragmentation and unsustainable use of land in the Union is jeopardizing the provision of several key ecosystem services, threatening biodiversity and increasing Europe’s vulnerability to climate change and natural disasters. It is also exacerbating soil degradation and desertification.'
Furthermore, Priority objective 7 (To improve environmental integration and policy coherence), paragraph 87, offers ample space for fragmentation to play a role in more effective integration of environmental and climate-related considerations into other policies: 'Incorporation of the Green Infrastructure can also help to overcome the fragmentation of habitats, preserve and restore ecological connectivity, enhance ecosystem resilience and thereby ensure the continued provision of ecosystem services, including carbon sequestration, and climate adaptation, while providing healthier environments and recreational spaces for people to enjoy.'
The EU 2020 Biodiversity Strategy, specifically Target 2, indirectly addresses fragmentation of ecosystems and habitats as it requires that 'by 2020, ecosystems and their services are maintained and enhanced by establishing green infrastructure and restoring at least 15% of degraded ecosystems'.
Reducing fragmentation also contributes to all other targets of the EU Biodiversity strategy, such as to Target 1 concerning the full implementation of the Birds and the Habitats Directives. In particular, paragraph 1 of Article 3 of the Habitats Directive sets up the legal framework for the Natura 2000 network, whereas paragraph 3 states that 'Where they consider it necessary, Member States shall endeavour to improve the ecological coherence of Natura 2000 by maintaining, and where appropriate developing, features of the landscape which are of major importance for wild fauna and flora, as referred to in Article 10.'
In addition, Article 6.4 of the Habitats Directive stipulates that Member States are to take 'all compensatory measures necessary to ensure that the overall coherence of the Natura 2000 network is protected'. Article 10 of the Habitats Directive and Article 3 of the Birds Directive also include more general connectivity provisions that relate to land use planning and development policies. Work on fragmentation of ecosystems and habitats also contributes to targets 3 and 4 of the EU 2020 Biodiversity Strategy concerning maintaining and enhancing biodiversity in the wider countryside (and the marine environment).
[1] European Environment Agency, 2014, Fragmentation: Overview of the knowledge base in the field of habitat and landscape fragmentation
None of the existing EU policies set quantitative targets for reducing and/or measuring the harmful impacts of fragmentation of ecosystems. The EU 2020 Biodiversity Strategy, specifically Target 2, directly addresses fragmentation of ecosystems and habitats as it requires that 'by 2020, ecosystems and their services are maintained and enhanced by establishing green infrastructure and restoring at least 15 % of degraded ecosystems'.
But combating fragmentation contributes to all other targets of the EU Biodiversity strategy as well, such as to Target 1 concerning the full implementation of the Birds and the Habitats Directives. In particular, paragraph 1 of Article 3 of the Habitats Directive sets up the legal framework for the Natura 2000 network, whereas paragraph 3 states that 'Where they consider it necessary, Member States shall endeavour to improve the ecological coherence of Natura 2000 by maintaining, and where appropriate developing, features of the landscape which are of major importance for wild fauna and flora, as referred to in Article 10.'
In addition, Article 6.4 stipulates that Member States are to take 'all compensatory measures necessary to ensure that the overall coherence of Natura 2000 is protected'. Article 10 of the Habitats Directive and Article 3 of the Birds Directive also include more general connectivity provisions that relate to land use planning and development policies. Work on fragmentation of ecosystems and habitats also contributes to targets 3 and 4 of the EU 2020 Biodiversity Strategy concerning maintaining and enhancing biodiversity in the wider countryside and the marine environment.
Calculation of the effective mesh size (meff) is based on three spatial datasets: 1) the 'landscape' extent, 2) the Fragmentation Geometry (FG) (landscape elements representing man-made barriers) and 3) reporting units (spatial units for which meff is calculated). The following steps are followed in computing the indicator.
1) Landscape extent:
The 'landscape' for the calculation of meff is the seamless area of Europe. The input to this step is the Copernicus High Resolution Layer (HRL) on Imperviousness Density (IMD) from 2012[1].
2) Fragmentation Geometry:
Fragmentation Geometries are man-made landscape elements, which divide the landscape into unconnected patches. Only anthropogenic elements are considered because the indicator addresses fragmentation of the landscape from urban areas and transport infrastructure (roads and rails).
2.1 Fragmentation Geometry — built up areas:
The build-up areas are excluded during the 'landscape extent' preparation step. From this layer, a binary mask is created and pixels with IMD value > 30 % are deleted from the dataset.
2.2 Fragmentation Geometry — road network:
The dataset representing the transportation network must meet the following technical requirements:
The Open Street Maps (OSM) dataset[1] was selected as input to process the road network Fragmenting Geometry. The following roads/rails classes were included:
Definition of OSM road classes:
Class 0 — a motorway is a major highway with restricted access to adjacent properties, designed for motorised vehicles, normally equipped with a minimum of four or more lanes. In most cases, the motorway is a dual carriageway, which means that the traffic for each direction is separated by a central barrier or strip of land and the whole infrastructure is often fenced.
Class 1 — trunks are important roads that aren’t motorways. Often suitable for long journeys with relatively high speed.
Class 2 — primary road, generally linking larger towns.
Class 3 — secondary road, generally linking smaller towns and villages
A tertiary road class is generally used for roads wider than 4 metres in width that is not included in the previous classes.
The line vectors were buffered according to the road classes in order to create polygon objects. Buffer sizes were selected according to the road class they represent. Buffering was also applied to prevent small topological inconsistencies in the OSM dataset.
Table 1: Buffers applied to the various OSM road and railroad classes:
|
OSM road class |
Buffer width [in m] on either side of the roads |
|
motorways and motorways links |
15 |
|
trunk and trunk links |
10 |
|
primary roads and primary roads links |
7.5 |
|
secondary roads and secondary roads links |
5 |
|
tertiary roads and tertiary roads links |
2.5 |
|
Railroads |
2 |
The result of step 2 is the Fragmentation Geometry layer that contains landscape patches (i.e. polygons representing the remaining non fragmented areas) and gaps (no value), in locations where Fragmentation Geometries were deleted from the landscape.
Step 3) Calculation of meff
The meff values are calculated for all reporting units. The reporting units are 1 km2 grid cells corresponding to the EEA’s accounting grid. Note, any regular (i.e. larger or smaller grids) or irregular (e.g. NUTS regions) reporting units can be chosen for the calculation as long as the spatial detail is satisfactory for the topic the indicator should support. To calculate meff, the Cross Boundary Calculation (CBC) procedure is used (Moser et al., 2007). In the CBC process, not only the area of the landscape patch that falls inside the reporting unit is input to the computation, but the whole area of that given landscape patch is accounted for (see image below). Hence, the borders of analytical units themselves do not influence meff values (see detailed explanation in Moser et al. 2007).
The Copernicus High Resolution Layer (HRL) is based on satellite imagery classification. As such, there are areas assigned with no IMD values due to cloud coverage (satellite datasets are sometimes not cloud-free). These gaps in data are filled using the Corine Land Cover (CLC) dataset using the corresponding build up mask derived from CLC classes. These are:
The methodology is without any major uncertainty. Some critique might arise regarding the Fragmentation Geometries, which were included (or not included) as barriers. This is however not a methodological uncertainty of meff and seff, but is rather a matter of consciously addressing the spatial detail of the indicator.
Uncertainty of the Copernicus High Resolution Layer – Imperviousness (HRL IMD): clouds are contained in the data layer. Corresponding Copernicus Corine Land Cover (CLC) data are used for the map filling (see Methodology for gap filling section). Because the spatial resolutions of the HRL IMD and CLC data are different, the spatial detail of the indicator may be influenced for the cloudy area. The metadata layer is part of the indicator dataset indicating HRL IMD cloud areas.
Uncertainty of the Open Street Map (OSM): maturity, completeness and classification stability of the OSM dataset are critical features for monitoring indicator changes and trends. Based on the OSM stability analysis done in 2016 (see link below), these qualities have been confirmed. Nevertheless, as the OSM is a collaborative project providing crowd sourced data under the Open Database Licence, the dataset has to be carefully analysed before any subsequent indicator update.
Without rationale uncertainty
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/mobility-and-urbanisation-pressure-on-ecosystems/assessment or scan the QR code.
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